1. Field of the Invention
The present invention relates to an optical assembly, in particular, an optical assembly with transmitting and receiving functions.
2. Related Prior Art
One type of optical assemblies has a well-known configuration that emits the light with the first wavelength to an optical fiber and receives the light with the second wavelength from the same optical fiber, and such assembly is applied in the both directional optical communication. Conventional assembly with such functions provides a light-emitting device, first to third lenses, an optical filter, and a light-receiving device. Between the light-emitting device and the optical fiber is installed with the first lens, the optical filter, and the second lens in this order. The light with the first wavelength emitted from the light-emitting device is collimated by the first lens. The optical filter is configured to transmit the light with the first wavelength, and to reflect the light with the second wavelength. Thus, the light, emitted from the light-emitting device and transmitted through the optical filter, enters the second lens. The second lens concentrates this light onto the tip of the optical fiber.
On the other hand, the light with the second wavelength emitted from the tip of the optical fiber is collimated by the second lens, reflected by the optical filter, and enters the third lens. The third lens focuses this light with the second wavelength on the light-receiving device. Japanese patent application published as JP-2003-322768A has disclosed such optical assembly.
However, the configuration above is necessary to install three lenses and one optical filter. Accordingly, these optical elements are hard to be installed within a small sized package, especially within the so-called co-axial package. Moreover, the number of elements intrinsically causes the cost increase.
Therefore, the present invention is to provide an optical assembly having both functions of the optical transmission and the optical reception to the single fiber.